The overall goal of the Virology Core is to facilitate the design and execution of the immunization and multiple low dose SIV mucosal challenge procedures that will be the basis of all projects in the program. Further, the Core will supply biostatistical expertise to all members of the Program. All the non-human primate studies will be carried out at the California National Primate Research Center (CNPRC). The Core will conduct penile, vaginal and rectal SIV transmission studies to determine if SIV-specific immunity elicited by the rAdSSIV vaccine increases the number of mucosal low-dose SIV inoculations required to establish productive systemic infection in rhesus macaques with or without pre-existing mucosal inflammation. Further we, will determine if immunity to AdShr prior to immunization with the rAdSSIV vaccine decreases the number of mucosal low-dose SIV inoculations required to establish productive systemic infection in rhesus macaques with or without pre-existing mucosal inflammation . The Core is critical to the P01 generally because it will manage animal studies, samples collection, processing and storage; produce AdShr stocks for monkey infection; analyze Ad5 shedding by virus isolation and PCR; AdS-specific immunity using antibody assays and T cell assays; If necessary, use the Merck Ad5 vector seed stocks to produce the E1-deleted Ad5-SIV vaccine for this study; perform SIV inoculation; monitor SIV infection status by PCR for plasma vRNA and PBMC vDNA; schedule and perform necropsies based on infection status (modeling studies) or experimental design (mechanism studies); provide statistical support for experimental design and data analysis. RELEVANCE (Seeinstructions): If we can produce an animal model that recapitulates the results of the STEP/Phambili trials then we will have the tools to dentify innate immune mechanisms important in vaccine-mediated protection against, or enhanced susceptibility to, mucosal SIV challenge.